Spain's Princess Cristina arrives at a makeshift courtroom for a corruption trial in Palma de Mallorca, Spain on Monday. Spain's Princess Cristina will make history as the first royal family member to face criminal charges since the monarchy was restored in 1975. She is accused of tax fraud related to a company she owned with her husband that allegedly helped fund the couple's lavish lifestyle.

The sister of Spain's King Felipe VI, Princess Cristina, appeared in court Monday as the first member of the Spanish royal family to stand trial since the nation’s monarchy was reestablished in 1978.

Princess Cristina, along with her husband Iñaki Urdangarin and 16 others, face trial after a years-long investigation into fraud surrounding Mr. Urdangarin’s nonprofit consultancy, Nóos, managed by Urdangarin and his business partner Diego Torres. Prosecutors say the foundation embezzled €6.2 million of public funds, mostly by securing work for the foundation through the provincial governments of Valencia and the Balearic Islands. Nóos was contracted to hold several sporting events there, but is accused of drastically overvaluing or never performing the services agreed upon and moving the money gained abroad or into front companies.

Cristina is charged with two counts of accessory to tax fraud, and Urdangarin faces charges for nine crimes including fraud, falsification, and embezzlement. Cristina faces a maximum of eight years in prison if convicted; Urdangarin more than 19. Both deny any wrongdoing.

Cristina was a member of the board of the Nóos Institute and co-owned the consulting firm Aizoon, called a "front company" by the case's judge, with Urdangarin. Prosecutors say Aizoon received money from Nóos, some of which was used by Cristina and her husband for vacations, parties, and more. Prosecutors say Cristina then failed to report tax on those expenses.

The accusations against the princess were brought by anticorruption group Manos Limpias (Clean Hands).

Cristina and Urdangarin’s lawyers, along with those for the other 16 defendants, maintained all parties’ innocence and asked that all charges be dropped, claiming Cristina committed no crime and should simply face a fine for tax evasion.

The trial began after years of investigation into Nóos and the activities of Cristina and Urdangarin sustained controversy for Spain’s monarchy. In 2011, Cristina and her husband were barred from all Spanish crown events and excused from their royal duties. The couple and their children moved to Geneva in 2013, but incurred the use of Spanish tax money for their security detail. And Cristina’s brother, King Felipe VI, stripped his sister and Urdangarin of their titles of Duchess and Duke of Palma de Mallorca last year.

The investigation, along with persistent economic problems and the abdication of the Spanish throne by long-reigning Juan Carlos I in 2014, have caused support for the nation’s monarchy to fall; the royal family’s confidence rating fell to only 3.72 out of 10 in 2014 after annually scoring above 5 from 1994 through 2010. Since Felipe’s ascension, though, the new king has topped public-opinion polls amid his retooling of the crown, though growing sentiment for Catalonian secession could again hurt the monarchy’s image.

The trial will adjourn until February when testimony is set begin, and is expected to run through June with possible sentences to be handed down later this year.